In the past, the conventional approach to the fabrication of a rocket motor case with an integral wound nozzle has been to select a helix wind angle that satisfies the relation: EQU helix angle=sin.sup.-1 Rt/Rc
where
Rt=Radius @ throat PA1 Rc=Radius of Cylinder.
The fiber that is wound on the mandrel is placed under tension and follows a path on the mandrel surface over the dome for the housing, through the throat section and along the expansion cone such as illustrated in FIG. 1. The winding of the rocket motor case and integrally wound nozzle continues until the mandrel is covered with sufficient material of the fiber to carry the loads and perform the function of a rocket motor case with an integral nozzle.
As can be seen, the winding of a rocket motor case with an integral nozzle is limited by the procedures of the prior art due to the helix angles that can be used to make the integral rocket motor case and nozzle using the wrapping procedures illustrated in FIG. 1. Using the helix angles of the type of the prior art, integral nozzle and rocket motor case fabrication are limited and when a large length to diameter rocket motor case with an integral nozzle is required, the rocket motor case utilizing the helix angles in conventional structure does not allow the rocket motor case with the integral nozzle to have sufficient axial stiffness to provide the stiffness required for a rocket motor case of the type needed.
Therefore, it is an object of this invention to provide a method for making a rocket motor case with an integral nozzle that can be wound and still provide the axial stiffness needed.
Another object of this invention is to provide a method for making an integral rocket motor case and nozzle in which the apparatus used to wind the rocket motor case and integral nozzle is conventional apparatus.
Still another object of this invention is to provide a method for making a rocket motor case with integral nozzle in which the length to diameter ratio is about 15-20 to 1.
Still a further object of this invention is to provide a method for making a rocket motor case with an integral nozzle in which the fibers are oriented at about 5 to 11 degrees relative to the axis of the rocket motor case to provide stiffness.
Other objects and advantages of this invention will be obvious to those skilled in this art.